Most chip card readers operate by means of a microprocessor that is powerful enough to enable, firstly, control over communications between the card and the reader and, secondly, communications between the reader and the microcomputer. The difficulty of communications between the card and the microcomputer lies firstly in the absence of synchronization between the operation of the card and the operation of the microcomputer. The difficulty in communications between the card and the microcomputer lies secondly in the fact that, at times when the card is communicating with the card reader, the microcomputer may be in the process of performing tasks other than that of communications with the reader.
The presence of a microprocessor in the reader is, therefore, generally considered to be necessary for the management of the exchanges. However, it is relatively expensive.